From Georgia Firearm, Knife, and Weapon Law Compendium - Robert Todd Bergin
"A license holder may carry in a National Park and a National Wildlife Refuge. On February 10, 2010, what is often referred to as "National Park Carry" wend into effect. Basically, if a license holder carries a permit or license that is recognized by the state in which the National Park or wildlife refuge is located, that license holder may carry on that property.
"Be careful, however. Most buildings in a National Forest, such as a ranger station or visitor center would be considered a federal building, and any open or concealed carry would be prohibited.
National Forests - same rules apply
This echos NavyLCDR's response in if state allows conceal carry, so will park.